The present invention relates to rapid action type switches, and more particularly, the invention relates to such switches with two contact make and break points per line connection to be made.
Snap action type switches are known in many configurations, whereby particularly the contact making and breaking for a single electric current path involves two stationary contacts cooperating with two movable contacts on a single bridge. See, for example, German printed patent applications Nos. 1,082,653; 1,169,009; 2,543,022, German Pat. No. 1,135,547 and U.S. Pat. Nos. 1,380,595 and 2,758,169.
The Swiss Pat. No. 385,963 discloses a snap action or quick throw type switch which is constructed to close one electrical circuit and open a second one in one operating state, while the situation is reversed in the opposite operating state. The switching action on each circuit involves two contact make or break points in order to increase the power that can be controlled by a single switch.
The British Pat. No. 1,114,630 discloses a quick action switch which includes means for forcing the contacts into an open position if the operating spring fails entirely or is to weak to open the contacts because, for example, the contacts are cold welded together. The U.S. Pat. No. 2,758,169 discloses a rapid action switch having two contact bridges only one of which at a time engages the stationary contacts. The contact surfaces of the respective other bridge in the open state is inclined relative to its stationary counter contacts.
Generally speaking, it should be realized that it is desirable to construct the switch for obtaining self-cleaning action of the contacts, that is to say, the contacts should slightly move across each other during engagement requiring resilient mounting of contacts. On the other hand, the switch should be amenable to opening by force other than the snap action in order to permit opening even if the snap action spring fails or the contacts are welded together. If the contact bridge or carrier is resilient forced opening is difficult to achieve.